Summary Analysing Greek literary sources together with a selection of preserved ostraka, this article discusses the interrelationships between the prevention of hybris, the perceptions of tyranny, and the purposes of practising ostracism in fifth-century Athens. It will be proposed that the political decisions to organize ostrakophoriai were reactions to the threat posed by hybristic disposition of an individual – hence, ostracism played a role in detecting and punishing one’s motives and intentions. It will also be proposed that luxurious life-style was perceived by the Athenians both as a sign of Medism and of a hybristic disposition characteristic of a would-be-tyrant. Thus, profligate life-styles of political figures might have urged the Athenians to organise ostrakophoriai.